In the evolution of automobiles from motorized carriages to highly regulated and computerized devices for mass transportation, there has been a continuous pursuit of refinement. One aspect of this refinement has involved the transmission of torque from an internal combustion engine to a drive system of the automobile. Torque transmission has been accomplished by various gear or chain driven transmission systems alternatively drivingly connected to, or disconnected from, a source of motive power for driving member), such as an internal combustion engine. The connection/disconnection feature of the drive system typically is accomplished using a clutch. Since the mid-1950's, especially in the United States, clutches typically have been a fluid clutch or a torque convener. Owing to the inclusion of fluid torque transmitting coupling, enhanced refinement of the driving experience has been obtained. However, this refinement has come at the expense of lost efficiency.
To address this lost efficiency, the torque converter has become, itself, an object of greater refinement and recaptured efficiency. Oftentimes, a contemporary torque converter includes a friction clutch assembly associated with a driven member of the torque converter which, at preset loads and speeds, replaces the fluid coupling of the torque converter with a direct mechanical friction coupling. This friction-clutch feature is commonly referred to as a lock-up clutch.
In current torque converters equipped with lock-up clutches, efficiency has been recaptured, but a loss of refinement is experienced when the clutch is in lock-up mode and when the clutch is transitioning into and out of lock-up mode. This is especially true when lock-up clutch elements become worn and tolerances between various rotating and fixed elements increase/decrease in accord with their respective wear patterns. The inclusion of an intermediate plate and elastic damping members reduces stiffness and improves vibration isolation, but add rotational mass and complexity to the torque converter sub-assemblies. The intermediate plate, which may be in contact with the elastic damping members at the outer surfaces of those damping members, carries the inertia and centrifugal force due to high rotational speeds of operation, thereby requiring an increase in the thickness or added reinforcement to the intermediate plate.